The present invention relates generally to gravity loaders for loading packages and the like, such as into a truck/trailer, and more particularly, to a cantilevered telescopingly extendable gravity loader.
Gravity loaders are often implemented at loading docks for trucks, trailers or the like. The gravity loaders are extendable into a truck/trailer and angled downward such that gravitational forces cause packages to move down the loaders along a plurality of rollers. The gravity loaders may be extendable to reach further into the trailer, in order to minimize the manual lifting and carrying of the packages, and retractable to a stored position to minimize the space taken up by the loader when not in use. However, because of the substantial size and weight of these loaders, extension and retraction is often accomplished by powered extension and retraction systems, which are typically complicated and expensive devices.
Also, the rollers of the loader are typically along an upper edge of the sidewalls of the loader. As multiple packages travel down the loader, a backlog of packages may pile up at the outer end before the operator may remove the packages from the loader and position the packages within the truck trailer. Because the rollers are positioned along the upper edge of the sidewalls, the pile up of packages may result in one or more packages being pushed off the loader.
Additionally, because gravity loaders are angled to provide a slope for the packages to travel down along, the discharge end of the conveyor may be positioned low and near the ground. A worker has to bend over to pick up the packages to move them to an appropriate place in the truck. Such bending and lifting is difficult and may result in injury to the worker. In some cases, obstacles, such as packages, supports or the like, may be positioned along the floor of the truck trailer. There may not be sufficient clearance of the obstacles to provide a sufficient angle or slope of the loader to cause the packages to travel downwardly along the rollers of the loader under the action of gravity.
The present invention is intended to provide a cantilevered telescopic extendable gravity loader for loading packages into a truck trailer or the like. The gravity loader includes at least one section and is nested, such that the section or sections may be retracted into a base structure. A plurality of rollers of the loader may be positioned below an upper portion of the sidewalls of the loader, such that packages are not prone to be dislodged from the loader. A user interface section may be provided at a forward end of the loader to ease raising and lowering of the packages to a desired height before the packages are manually removed from the loader.
According to an aspect of the present invention, an extendable conveyor or loader includes a support structure and an extendable conveyor section supported in a cantilevered manner. The extendable conveyor section includes at least one extendable conveyor unit which is mechanically extendable between an extended position and a retracted position nested within the extendable conveyor section and support structure. The extendable conveyor units have an upper portion along opposite sides thereof. A plurality of rollers are supported at the extendable conveyor unit defining a gravity operator conveying surface. A user interface section is provided at a forward end of the extendable conveyor section. The user interface section includes a driven conveying surface, such as a belt conveyor or the like. In a preferred embodiment, the extendable conveyor units and the conveying surface are orientated at an angle with respect to horizontal which is between at least approximately 3xc2x0 and at most approximately 5xc2x0.
According to another aspect of the present invention, the extendable conveyor sections have inverted generally U-shaped sides which include an outer sidewall, an inner sidewall and an upper portion. The extendable sections have a plurality of rollers mounted to the inner sidewalls and below the upper portion. Preferably, a cantilevered support roller is positioned at an upper portion of at least one extendable section and provides cantilevered support of the section via rolling engagement along the upper portion of the sidewalls of another, inwardly or rearwardly adjacent inner section.
According to yet another aspect of the present invention, the extendable conveyor section includes at least two conveyor units which are downwardly angled and extendable to an extended position via gravitational forces. At least one support roller is positioned between a rearwardly positioned section and a forwardly positioned section and provides rolling support of the forwardly positioned section as it is extended and retracted relative to the rearwardly positioned section. The support rollers are frictionally tuned such that the conveyor units extend forwardly at different speeds relative to one another, whereby extension of one unit relative to another varies in response to the frictional resistance of the corresponding support rollers. Preferably, the forwardly positioned conveyor unit extends at a slower pace than one or more rearwardly positioned units.
According to yet another aspect of the present invention, a user interface section is supported in a cantilevered manner from the extendable conveyor unit. The user interface section is vertically adjustable about a substantially horizontal axis via an actuator. The actuator is mounted to at least one elastic member at the conveyor unit. The elastic member is extendable and/or compressible in response to resistance to vertical movement of the user interface section being encountered as the actuator vertically adjusts the user interface section. A limit switch may be operable to deactivate the actuator in response to a threshold amount of extension or compression of the elastic member. Preferably, the elastic member comprises a pair of compression springs, whereby the first compression spring is compressible in response to resistance to downward movement of the user interface section and a second compression spring is compressible in response to resistance to upward movement of the user interface section.
According to still yet another aspect of the present invention, a user interface section is supported in a cantilevered manner from an extendable conveyor unit. The user interface section is vertically adjustable about a substantially horizontal axis via an actuator. A vertical assist device is operable to assist the actuator in vertically adjusting the user interface section. Preferably, the vertical assist device comprises a pair of gas springs positioned along the linear actuator.
The present invention provides a cantilevered extendable gravity loader which provides optimal extension rates and package travel rates, while providing clearance of obstacles within the truck trailer. Retraction of the extendable units is accomplished via a low cost retraction system comprising a winch and a cable. The extendable units are fully nested and provide raised sidewalls above the rollers to prevent packages from falling off the loader, while also providing a minimal drop off between the conveying surfaces of the units and a minimal height of the units. The actuator for the user interface section is preferably mounted within the extendable unit at one or more compression springs to protect the actuator from impact or shock. The lift assist devices assist the actuator in vertically adjusting the user interface section, such that a smaller moment arm is needed at the user interface section to raise and lower the section.